Try it freekboy31. But I doubt it can overcome the limitations of your hardware (if the problem of lag comes from that).

Phantomboy, you will love it! It's worth the efforts to learn a new software. For my part, I'm still struggling to discover all the interface and the features (I've never used sofwares like that, beginner in that domain), and I haven't yet started to dive in the doc to discover the API (and there's a lot of possibilities as we can use scripting (Python) in Natron).